Field of the Invention
The invention relates to an exhaust treatment apparatus for an engine. Specifically, the invention relates to an exhaust treatment apparatus for an engine that suppresses thermal damage to an electrothermal ignition apparatus.
Description of Related Art
Conventionally, there exists an exhaust treatment apparatus for an engine structured as follows (e.g., see Japanese patent application (Kokai) JP 2012-188972 A (FIGS. 1A and 2)).
The exhaust treatment apparatus for an engine includes: an exhaust passage; an oxidation catalyst disposed in the exhaust passage; a combustible gas generator; a combustible gas supplying passage; a heat dissipation port opened upstream in the exhaust passage from the oxidation catalyst and in a downstream part in the combustible gas supplying passage, the exhaust passage and the combustible gas supplying passage communicating with each other through the heat dissipation port; and an electrothermal ignition apparatus disposed in the combustible gas supplying passage. Heat of flaming combustion of combustible gas ignited by the electrothermal ignition apparatus is supplied to the exhaust passage, to raise the temperature of exhaust in the exhaust passage.
The exhaust treatment apparatus of this type is advantageous in that, even when the temperature of exhaust is relatively low, the temperature of the exhaust is raised by heat of flaming combustion of combustible gas, whereby the oxidation catalyst can be activated.
However, this conventional technique is disadvantageous in that it does not have any unit that cools the electrothermal ignition apparatus.